A recent increased awareness of security and greater needs for IT (Information Technology) based on-site management have led to introduction of monitoring systems employing monitoring cameras into various places. These monitoring systems have a function to detect a position of an object being monitored by performing image analysis processing on images output by a monitoring camera and then utilizing the processing results.
As a technique related to positional detection of objects being monitored in such monitoring systems, PTL 1 discloses an apparatus which performs data processing on images taken by an infrared camera and a PTZ (Pan Tilt Zoom) camera which obtain moving images. This apparatus identifies a monitoring target, i.e. a person smoking while walking, then uses the PTZ camera to track the identified person who is smoking while walking.
In addition, PTL 2 discloses an apparatus which is capable of detecting the position of a person by precisely combining a plurality of sets of positional information on the person whose images have been taken by a plurality of monitoring cameras, even if these sets of positional information have a detection error.
In addition, PTL 3 discloses an apparatus which determines that an object i is identical to an object j if a difference between coordinates of a gravity center of the object i at a time k and coordinates of a gravity center of the object j at a time (k+1) is less than a predetermined value.